Ant biology: September 2014 Archives

Ants and Disease



Hello, this is a very strange situation but I have a 10 month old baby in my home and I am concerned.

A couple of weeks ago I went in to the backyard and noticed my dog was playing with something unfamiliar. As I walked towards it I realized that it was a bird. This bird must have been there for awhile because it was unable to move, and had defecated so much that ants were (I'm sorry for the graphic details) actually crawling inside of this poor bird and apparently eating the fecal matter. This poor guy was obviously in a significant amount of pain so we had to do something very sad to stop it from suffering any longer.

This just so happened to have occurred next to a wall in our home that is the exterior wall to our dining room where we eat and where my 10 month old's high chair is. Today, I was eating at our table and some of my paper work and pens were sitting on top of it. As I was picking up my plate I noticed the same species of tiny little ants crawling all over the table and my paper work. There was not even any food or anything on the table that could have lured them there. I instantly took my son upstairs, and began disinfecting the table, vacuuming and such.

I do not know anything about ants but my concern is that these ants might be carrying disease from the bird. Can you please tell me if I need to be worried about this? They are the tiniest little transparent orangish colored ants. We live on Oahu, in Hawaii. Thank you very much for your time.

Alix

Ok, Alix. I've got good news and bad news.

The bad news: Ants (just like any animal that moves from one place to another) can transmit infectious bacteria, including Salmonella and Staphylococcus. (I'm not trying to throw your dog under the bus by any means, but your dog is definitely more of a vector for bacteria coming in from outside than these ants.) As indicated in a quick literature search (click here ), it's been reported at least as far back as 1914 (Wheeler) that if an ant walks through an area densely populated with infectious bacteria, they track it along in quantities large enough to show up in a petri dish.

The good news: Petri dishes don't have immune systems. The quantities of bacteria ants transport and slough off as they saunter across your counter tops will probably be small compared to the infectious dose for healthy humans. The quantities of bacteria that remain on the ants' feet after taking the thousands of little ant-steps between a source of infection and your table would presumably knock off the vast majority of the bacteria, leaving too few to constitute an infectious dose.

So what I'm trying to say is: thought it is theoretically possible for ants to transmit infectious bacteria to humans, as far as I'm aware (other members of this blog, please speak up if you know better!) there are no records of ants being definitively implicated in someone catching a disease. As best as I can tell, all of the articles that reference ants' potential to be vectors for infectious bacteria are based upon laboratory studies in which nothing besides some agar in a petri dish got sick. Ants, as you know, are quite common, so it seems to me that if they were serious actual (as opposed to potential) disease vectors, we'd have heard about it.

A well-intentioned tangent: This is, of course, neither a child-rearing nor a health advice blog, but I think this recent article on the "Hygiene Hypothesis" makes a good case for not keeping too sterile a house:
http://time.com/2828841/why-you-should-let-kids-eat-dirt/
Some arguments, both pro- and con- Hygiene Hypothesis haven't been rigorously scientifically tested, so take everything you read with a grain of salt...or a pinch of dirt.

Hope this helps!
Jesse Czekanski-Moir & the AntAsk Team

Ant social status



Hi, I was curious if ants have a social status within their sub sectors (worker, male). How do they obtain a higher status? And if so does this give them more privilages (ie a bigger living space, more food, first breeding rights).

HUB


Dear Hub,

Thanks for writing to the AntBlog! We contacted an expert on many aspects of ant biology (behavior, colony reproduction, nest architecture, population dynamics, among others), Dr. Walter Tschinkel; here is what he had to say:

"Hello Hubert,
You asked AntBlog whether ant have social status within their colonies, and whether such status might be connected to certain individual advantages and benefits.
The simplest answer is that social status in the sense that we know it within vertebrate societies does not exist in ants. It is helpful to think of ant colonies as analogs to organisms (hence, we often call them superorganisms). Every individual is engaged in helping the colony produce more colonies, just as every cell in an organism is engaged in helping produce more of that organism. In the ants, there is only one (or a few) individual(s) capable of direct reproduction (the queen), while in an organism, only the germ-line cells in the gonads are capable of making gametes and subsequently more organisms. In this light, you can see that different sectors of the colony may be allocated differing amounts of resources, but such allocation serves the needs of the colony as a whole, rather than any individual within it. The individual ants making up the colony are simply the machinery needed to make more colonies.
One of the basic mechanisms that organizes colony function is division of labor (or function). The most basic division of function or labor is reproductive -- most of the ants in a colony are more or less sterile workers, while only one (or a few) individual is capable of mating and laying eggs. Most of these eggs develop into more workers because workers are short-lived and are continuously replaced, whereas the queen has a long life span (in many cases, equal to the life span of the colony). The second principle that organizes the colony is that the workers change jobs as they age. Young workers mostly take care of larvae and pupae, and as they age they switch to more general nest maintenance, food processing, transport within the nest and so on. Only the oldest workers leave the nest to forage, bringing back food for the rest of the colony. Once they begin foraging, their life expectancy is very short (a few weeks).
This change of jobs parallels an upward or outward movement of the worker within the nest. Young workers are born in the deeper parts of the nest, move upward as they age and change jobs, and finally appear near the surface, whereupon they become defenders and foragers during the last part of their lives. There is thus a continuous upward and outward flow of workers. The image here shows a cast of the nest of the Florida harvester ant, Pogonomyrmex badius, and summarizes these movement and labor patterns within the nest.

Once you see the parallels between organisms and superorganisms, you see that division of function or labor is central to both, and that differences in allocation serve the entire entity. The relative size and activity of the liver, or kidneys or circulatory system of an organism serves the entire organism, and any deviation from some norm can be detrimental to the function and fitness of the organism. Similarly, the patterns of division of labor in ant colonies serves the success and fitness of the colony as a whole. The workers are just the gears in that machine."

We hope this answers your question,

Walter Tschinkel, Flavia Esteves & the AntAsk Team


My name is Joseph, a senior biologist at the University of Scranton. I am currently conducting research on morphometric of ants, but we are having some issues. I was curious if you had any papers on the histology of ants, specific on the nervous system or their notochord. Any species will do at the moment, we are just used to looking at mammalian tissue, and not insect samples. Hope to hear back from you soon!

Joey


Hello Joseph,

Thanks for writing! We contacted an expert on the nervous system of ants, Dr. Wulfila Gronenberg; here is what he had to say:

"Dear Joseph,

the nervous systems of insects has been well described for many taxa, and ants are no exception. The basic design is not unlike what you see in vertebrates - they have a brain with visual, olfactory, tactile and other centers including higher order central processing centers, and the have a ventral nerve cord analogous (and probably homologous) to the vertebrate spinal cord and which comprises the sensory and motor centers that control walking, flight (in winged males and females) and abdominal functions. If you want to learn more about ant nervous systems I suggest a review paper that I have written a few years ago:

Gronenberg W (2008) Structure and function of ant (Hymenoptera: Formicidae) brains: Strength in numbers. Myrmecological News 11:25-36.

If you (or anybody else) have difficulties getting hold of the paper, just send me an email: wulfi@neurobio.arizona.edu.
If your question was more about histological and technical aspects (how to dissect, stain or measure ant brains), please let me know and I can point out some more specific information to you.

All the best"

Wulfila Gronenberg, Flavia Esteves & the AntAsk Team

p.s. Joseph, if you create an account on Myrmecological News (for free), you can download Gronenberg's paper.

Cohabiting ants


Hi there, loving your page!

I am on holiday in Andalucia, southern Spain, and right by our front door there is a colony of what look like harvester ants. No more than fifteen centimetres away there are some holes from which some very tiny red ants emerge, about a quarter of the size of the smallest harvester ants. Are these two separate colonies, or different types of the same ant? They don't look related and they don't appear to cross into each others territory. I would have thought they'd be fighting all the time if they're not related. Why might this be? Are their diets different enough that they aren't in competition? Sorry to bombard you with questions!

Kind regards,

Ian


Dear Ian,

Greetings from San Francisco, and thanks for writing! We contacted an expert on taxonomy and ecology of Europe and Macaronesia ant species, Dr. Xavier Espadaler; here is what he had to say:

"It is not an unusual situation for different ant species to have nest entrances rather close. Coexistence is a possibility; fighting is another possibility. But if the two societies are already nesting close to each other, it is likely that they differ in some way, in their daily activity cycles, or in their food habits.

It is possible that the harvesting ants (Messor) are living close to a Pheidole pallidula nest. This last species is all too common in AndalucĂ­a. Their nest, with one or a few entrances, is usually surrounded by the tiny remains of the scavenging they do upon any kind of arthropod remains or corpses; they may capture living prey as well, if small enough. The remains look like a dark zone, somewhat semicircular, bordering the nest entrance. If you are able to look at them under a magnifier, you would see shining heads, wing or leg or thorax fragments, that are the non edible parts of their foraging."

Hope this helps,

Xavier Espadaler, Flavia Esteves, & the AntAsk Team

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